Patterning Embryos in 4D

Question 1

What are the three uses of animal models?

Answer 1

Understand biological phenomena
Distinguish between genetic and environmental contributions to a disorder
Explore causes and treatments for human diseases

Question 2

How does a single-celled egg become a complex multi-cellular 3D organism?

Answer 2

Generating different cell types
Assigning them different shapes and functions
Patterning the embryo in 3D through time

Question 3

Which process is defined as the developmental mechanisms that cause cells that are initially equal to acquire different identities?

Answer 3

Patterning

Question 4

Which process is defined as the ability to respond to an inducing signal?

Answer 4

Competence

Question 5

What is the process where signals from a cell alter the fate of another cell?

Answer 5

Induction

Question 6

Pluripotent cells are (uncommitted/committed) and multipotent cells are (uncommitted/committed)

Answer 6

Uncommitted; committed

Question 7

Identify the structure to its cell potential:
i. Blastula stage
ii. Limb bud
iii. Single cell to 8-cell morula
iv. Arm

Answer 7

i. Pluripotent
ii. Multipotent
iii. Totipotent
iv. Unipotent

Question 8

What type of cell follows a specific pathway if left alone, can respond to other signals and whose fate is flexible?

Answer 8

Specified cell

Question 9

What type of cell can no longer change its fate in response to new signals and whose fate is irreversible?

Answer 9

Determined cell

Question 10

What type of cell is mature and specialized, in its final developmental stage and end of lineage?

Answer 10

Differentiated cell

Question 11

What are the three types of specification?

Answer 11

Autonomous, syncytial, conditional

Question 12

Which specification depends on asymmetric distribution of cytoplasmic content and cells developing according to early fate?

Answer 12

Autonomous

Question 13

In autonomous specification, if a blastomere is removed, can it be replaced?

Answer 13

No it cannot, each blastomere already contains positional information

Question 14

Why does a symmetrical parent cell become polarized?

Answer 14

Asymmetric segregation of fate determinants

Question 15

What does the production of distinct daughter cells depend on in autonomous specification?

Answer 15

Alignment of mitotic spindle

Question 16

Spindle perpendicular to determination gradient and metaphase plate parallel to determination gradient leads to (identical/unidentical) daughter cells

Answer 16

Identical

Question 17

Spindle parallel to determination gradient and metaphase plate perpendicular to determination gradient leads to (identical/unidentical) daughter cells

Answer 17

Unidentical

Question 18

Which specification is associated with nuclear division without cytokinesis, exposed to gradients of cytoplasmic contents?

Answer 18

Syncytial

Question 19

Which specification depends on environmental conditions and external signals that cause the activation of different transcription factors?

Answer 19

Conditional

Question 20

In which specification can cells compensate for missing cells?

Answer 20

Conditional

Question 21

What experiment was done to monitor differentiation

Answer 21

Single cell RNA sequencing

Question 22

The results of the single cell RNA sequencing experiment showed that gastrulation (epiblast cells) gave way to which cells?

Answer 22

Mesoderm, ectoderm, endoderm

Question 23

Ectoderm differentiation gives rise to which cells?

Answer 23

Neural ectoderm

Question 24

In an experiment where red cells from blastula become muscle cells and yellow cells from blastula become neurons, what happens when a red cell and yellow cells are mixed?

Answer 24

Either red cell becomes muscle and yellow cells become neurons OR red and yellow cells all become neurons

Question 25

What was the process that enabled the observation of Fgf8 in the optic vesicle?

Answer 25

In situ hybridization

Question 26

What are the steps of in situ hybridization?

Answer 26

Synthesize probe with Digoxigenin and RNA complementary to target mRNA Introduce probe into the cell Wash the cell and add anti-Digoxigenin antibody conjugated with alkaline phosphatase Antibody attaches to RNA and causes color reaction that gives purple color

Question 27

What was done to observe the role of the optic vesicle in lens induction?

Answer 27

Signaling molecule for Fgf8 expression was moved from the optic vesicle to the lens - Fgf8 expressed in the lens Removal of optic vesicle - no induction of lens

Question 28

What are the inductive signals of the signaling cell?

Answer 28

Ligands

Question 29

What are the inductive signals from the receiving cell?

Answer 29

Receptors conduct transduction mechanism (receptor to nucleus), leading to change in gene expression and cell shape

Question 30

What are the types of signaling?

Answer 30

Autocrine, paracrine, endocrine, juxtacrine

Question 31

Retinoic acid pathway is an example of what signaling?

Answer 31

Endocrine

Question 32

Notch-Delta signaling is an example of what signaling?

Answer 32

Juxtacrine

Question 33

What is the concept of Notch-Delta?

Answer 33

Delta acts as a ligand and binds to Notch, which cleaves inside the cell NICD turns on transcription of genes in the nucleus

Question 34

What is the difference between paracrine and juxtacrine signaling?

Answer 34

Juxtacrine requires that the receptors of both cells are connected Paracrine requires that the ligand from one cell moves to the receptor of another cell

Question 35

Bone morphogenetic proteins, Sonic Hedgehog, Wnt and Fibroblast Growth Factor pathways are all examples of what signaling?

Answer 35

Paracrine

Question 36

What is the mechanism of bone morphogenetic protein pathway?

Answer 36

Ligand forms complex with Type I and II receptors Type II receptor phosphorylates type I receptor Type I receptor phosphorylates R-SMAD Phosphorylated R-SMAD forms dimer with Co-SMAD Dimer translocates to the nucleus and activates transcription of genes

Question 37

What is the mechanism of Shh pathway?

Answer 37

Shh binds to Ptc receptor Smo is released from Ptc effect and is activated Smo activates Gii transcription factors in the nucleus

Question 38

What is the mechanism of Wnt pathway?

Answer 38

Wnt binds to receptor and stops degradation of beta-catenin Beta-catenin translocates to the nucleus and activates gene expression

Question 39

What are the kinds of ligands?

Answer 39

Ligands that diffuse directly into the cell Ligands that bind to cell surface receptors Morphogens

Question 40

Estrogen, glucocorticoids and retinoic acid are what kind of ligands?

Answer 40

Ligands that diffuse into the cell

Question 41

Shh, BMPs and bicoid are what kind of ligands?

Answer 41

Morphogens

Question 42

FGFs and Wnt are what kind of ligands?

Answer 42

Ligands that bind to cell surface receptors

Question 43

Morphogens are ____________ ligands that cause different responses at different distances/concentrations

Answer 43

Secreted

Question 44

What are the three types of morphogens?

Answer 44

Signaling molecules, transcription factors, small diffusible molecules

Question 45

Shh, BMP and activin are what type of morphogens?

Answer 45

Signaling molecules

Question 46

Bicoid is what type of morphogen?

Answer 46

Transcription factor

Question 47

Retinoic acid is what type of morphogen?

Answer 47

Small diffusible molecule

Question 48

Which of the following is/are not characteristics of a morphogen? a. Forms a concentration gradient b. Activates target genes below concentration threshold c. Each cell sees a different concentration

Answer 48

b

Question 49

Which proteins help morphogens move by disassociating and reassociating with them?

Answer 49

HSPGs